The invention relates to display devices, and more particularly, to display devices with digitizers.
There are many types of touch sensitive computer input devices currently used for the purpose of digitizing touch on or in conjunction with computer displays. Such devices measure the position of a position pointer or finger touch on the sensor surface. The position is used to generate coordinates for the purpose of interacting with the computer, for example in pointing to icons on the display, picking menu items, editing computer generated images, and feedback for input of hand-drawn characters and graphics.
Such devices which sense a human touch may use any number of technologies, including capacitive sensing, resistive sensing using a conductive overlay sheet, infrared sensing, acoustic wave sensing, and piezoelectric force sensing. Digitizers which use corded hand held position pointer such as pens typically use electromagnetic sensing, electrostatic sensing, resistive sensing, or sonic pulse sensing.
Devices responsive to human touch are typically used for cursor control application, for example pointing to display icons and selection menu items. Devices responsive to position pointer (usually a corded pen) are used to create or trace drawings, blueprints, or original art. These devices are also used for character or handwriting recognition. It is therefore desirable that the sensor reproduces the trace of the position pointer by some visual means so that the user has visual feedback.
Some of these devices are responsive to both human touch and position pointer touch, thereby providing the convenience of position pointer-based input, for example when writing on the screen, as well as the ease of human touch input, which does not require the user to find the position pointer and pick it up to use it.
FIG. 1 is a block diagram of a conventional display system with a digitizer. As shown, display system 100 comprises LCD module 110 and digitizer module 120. The LCD module 110 and the digitizer module 120 are coupled to the host system 130 via the corresponding interfaces 112 and 122 respectively. The digitizer module 120 requires an oscillator 124 disposed in the microcontroller 126 to generate scan timing signals (not shown) for the selection circuit 128, thereby performing scan operation of sensor array 129. FIG. 2 shows a conventional display device with digitizer. As shown, the display device 200 comprises a liquid crystal display (LCD) panel 220, aback light module 230, areflector240, a digitizer module 120, a back frame 260 and a position pointer 123, the digitizer module 120 and the position pointer 123 constructing a digitizer. The LCD module 110 and the digitizer module 120 are coupled to an external host system 130 via different interfaces 112, 122, such as two flexible printed circuit boards (FPCs). The conventional display device, however, has disadvantages of high cost, thickness and weight.